1. Field of the Invention
The present invention relates to a microcomputer and more specially to a microcomputer comprising a unit for storing that the result of an operation is "0".
2. Description of related art
Heretofore, some microcomputers include a unit for storing that the result of an operation is "0" (called "Z flag" hereinafter). For example, in the case that two operations A and B are continuously executed, the Z flag is set if the result of the operation A is 0, and the Z flag is reset if the result of the operation B is not 0. Accordingly, in order to know whether or not both the results of the serial operations A and B are "0", a complicated processing has been required. Specifically, the content of the Z flag is stored in a second memory unit after the execution of the operation A, and then, immediately after the execution of the following operation B a logical operation is executed between the content of the Z flag which stores the result of the operation B and the content of the second memory unit which store the result of the operation A.
Therefore, in the case of executing comparison or coincidence detection between two given data or numbers having a bit length longer than the bit length processed by a one-time operation of a microcomputer, each of the given numbers must be divided into two or more unitary portions having a bit length equal to or smaller than the bit length processed by one-time operation of the microcomputer, and comparison operations of the same number as the divisor of the data division must be sequentially carried out so that the results of the respective comparison operations are totalized. In addition, the above operation is executed in accordance with a programmed sequence. Accordingly, the longer the data to be compared becomes, the step number of a required program and the time necessary for execution of the operation are inevitably increased. In addition, a memory capacity for temporarily storing the results of the respective comparison operations is also increased.